Earlier there were only two kingdoms of plants and animals. Whittaker in 1969 suggested that bacteria should not be in plant kingdom and protozoa not in animal kingdom. He gave the five kingdom classification.
Monera: Single celled, no well formed nucleus (Prokaryotes). Example: Bacteria
Protoctista (Protista): Single celled with well formed nucleus (Eukaryotes). Example: Protozoa
Fungi: Eukaryotes, multi-celled, saprotrophs. Example: Mushroom
Plantae: Eukaryotes, multi-celled, autotrophs. Example: Fern and Tree
Animalia: Eukaryotes, multi-celled, heterotrophs. Example: Earthworm and cat
The kingdoms are further divided into divisions (as in bacteria, fungi and plantae) or phyla (as in Protoctista and Animalia). Every phylum includes several classes, Classes are divided into orders. Orders include families.
A family is made up of many genera (singular: genus). Every genus includes several species. Species are segregated from their related species under the same genus through reproductive barriers. This means that members of one species cannot interbreed with members of another species to produce fertile offspring.
Every organism belongs to one of the five kingdoms of life.
A. Kingdom MONERA includes microscopic, single celled organisms with cell wall, no proper nucleus. For example, All bacteria.
B. Kingdom PROTOCTISTA (PROTISTA) includes single celled organisms with well formed nucleus. For example, Amoeba, malarial parasite, Chlamydomonas.
C. Kingdom FUNGI includes multi-cellular or many celled organisms. The body is made of network (mycelium) of fine threads called hyphae. Fungi feed on dead decaying matter (saprotrophs). For example, Mushroom, yeast, bread mould.
D. Kingdom PLANTAE includes multi-cellular eukaryotes with:
- cellulose cell wall and chlorophyll present in their cells.
- Autotrophs and thus carry out photosynthesis.
E. Kingdom ANIMALIA includes organisms with the following characteristics:
- Multi-cellular, eukaryotes.
- Hetrotrophic so feed on plants or other animals.
- Possess special organs for locomotion or movement from one place to another.
- Possess nervous system with sense organs.